The Prius line has this, too. I think it's a cool novelty. In-car trip computers are, of course, no match for the old divide miles driven by gallons used method, but it is a nifty tool to see in a car.

Over 20,784 miles, my average in my Cadenza has been 25.3 MPG. I find the computer's tank average (I have mine set to reset automatically at each fill-up) is usually about an MPG off, my calculations--OK, Fuelly's-- though not always. Also, a trip must have been at least a mile before trip mileage is actually displayed.

Having that information pop up when you turn off the car is a great idea. But you know what would be brilliant? Have a similar screen pop up when you turn on the car. Would be really great to be reminded of the estimated remaining range each time I got in the car.